docs: def list_tags(userdata):
          """List all used macros within a UserData script.
  
          :param userdata: The UserData script.
          :type userdata: str
          """
          macros = re.findall('@(.*?)@', userdata)
          logging.info('List of available macros:')
          for macro in macros:
              logging.info('\t%r', macro)